1. Field of the Invention
The present invention relates to a powder container that contains powder therein, a toner cartridge that uses the powder container, a drawer tray to which the toner cartridge is attached, and an image forming apparatus in which the drawer tray is installed.
2. Description of the Related Art
In electrophotographic image forming apparatuses, such as copying machines, printers, facsimiles, or multifunction peripherals, a toner image is generally formed by a developing device by using a developer, called toner or carrier, so as to form an image. In this type of image forming apparatus, toner is consumed when a image is formed; therefore, a toner cartridge that contains toner is usually attached to the image forming apparatus and, if there is no toner in the cartridge, toner is supplied by replacing the cartridge with a new cartridge.
In one of the methods for attaching a toner cartridge to an image forming apparatus, a drawer tray is used to hold the toner cartridge. The drawer tray is attached to a frame provided on the apparatus body of the image forming apparatus in a horizontally movable manner with respect to the frame. When the drawer tray is moved toward a front side, the drawer tray can be drawn out of the image forming apparatus. Conversely, if the drawer tray is moved toward the apparatus, the drawer tray can be housed in the image forming apparatus. A drawer tray housing unit in the image forming apparatus has a fixing unit to which the toner cartridge is fixed; a sub hopper that temporarily holds toner discharged from the toner cartridge; and the like.
With a toner supply system that uses the above-described toner cartridge, in order to reduce a running cost, there is a user's requirement to use up the toner in the cartridge without leaving any toner therein. In one of the conventional methods that are used for toner cartridges, a screw called an auger is installed in the container and the auger is rotated to deliver toner to a discharging unit. In another conventional method, a container called a screw bottle in which protrusions are formed on the inner surface of the tubular container in a spiral manner is used, and the container is rotated to gradually convey toner to a discharging unit.
However, a conveyance system that uses the above-described auger is disadvantageous because it is necessary to install and rotate a screw in the container, which makes a structure of the conveyance system complex. Furthermore, because the auger forcibly conveys accumulated toner in this conveyance system, a large load is imposed on the toner, which may make the toner clump together or deteriorate. Moreover, installation of a screw in a replaceable container may cause a problem in that a cost for disposables becomes high and an increasing burden is imposed on the environment due to the consumption of resources.
In a conveyance system that uses a screw bottle, because it is not necessary to install a screw in the container, the structure becomes simple. However, because the container is used by being rotated in this conveyance system, the container usually has a shape such that an outlet is provided on one of the sides of the apparatus body of the cylindrical container (the shape of a bottle that is set sideways). Therefore, there are disadvantages in that an amount of toner that can be contained in a cylindrical container is less than that in a container having a shape of a rectangular parallelepiped and in that a cylindrical shape of the container may cause a user's grip to be hard or lost when the container is replaced.
Moreover, because the above-described cartridge or bottle is made of polyethylene terephthalate (PET) forming a PET container called a “hard bottle”, causing a serious problem in recycling the used containers associated with the replacement of cartridges or bottles. Specifically, a manufacturer collects used containers from users for reusing, recycling, or thermal disposal; however, because the volumes of used containers are large, logistic costs are high for a manufacturer to collect and convey used containers from users.
Moreover, if a collected container is to be refilled with developer for reusing, cleaning of the collected container is difficult and the efficiency for supplying toner is low; therefore, reusing the collected containers requires high cost.
According to the inventions disclosed in Japanese Patent Application Laid-open No. 2002-46843 and Japanese Patent Application Laid-open No. 2002-72645, a simple horizontally long box container is used, and toner is conveyed to a discharging unit due to the inertia of the toner when the container is moved in a reciprocating manner in the horizontal direction by an external device. According to the invention disclosed in Japanese Patent Application Laid-open No. 2002-72645, a container is made of a flexible material so that the volume of an empty container can be reduced, whereby disposal cost can be reduced. A method for moving a convex portion that is pressed against the bottom of the container is disclosed in Japanese Patent Application Laid-open No. H11-143195 as a method for discharging toner from the above-described flexible container. Another method for discharging toner from a toner container by rotating the shutter of the toner container, thereby the discharging opening thereof is opened or closed is disclosed in Japanese Patent Application Laid-open No. 2006-309147 and Japanese Patent Application Laid-open No. 2009-42567.
In view of the performance for maintenance, such as prevention of contamination due to toner during replacement of a container or easy replacement of a container, if the flexible container disclosed in Japanese Patent Application Laid-open No. 2002-72645 is used, it is preferable to install a shutter in the discharging unit that is provided below the container. However, for the shutter to be opened and closed, a space for moving the shutter is generally needed, and this has been an obstructive factor in the reduction in the space or the size of an image forming apparatus.
Thus, there is a need to provide a powder container and a toner cartridge that prevent powder from leaking out when the toner cartridge is attached or removed and that are suitable for space and size reduction and to provide a drawer tray and an image forming apparatus that use the powder container and the toner cartridge.